Reverse Circulation of Primary Cementing Jobs—Evaluation and Case History

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractDrilling in the Arctic can present a number of challenges even before the drilling begins. Among the challenges are logistic difficulties, weather extremes, and environmental sensitivities. To offset the production decline for natural gas in North America operators must confront these challenges by resuming exploration in the Arctic.The target in this case study is a well in the Paktoa field. The design challenge presented by this well was to drill the well to total depth (TD) with the lowest number of casing strings while avoiding remedial cementing operations. Given that the mud-weight window predicted for this wellbore was quite narrow, well planners determined that no fewer than five casing strings were needed to reach TD. Multiple casing strings can lead to tighter annuli and more challenging cementing operations.Using modeling software as an aid to cement design, planners determined that the cement on the first liner, from 1,300 to 2,600 ft, could not be circulated conventionally without breaking down the formation because of the high equivalent circulating density (ECD). The greatest contributor to the high ECD is the tight annulus of the liner lap. The model parameters were reversed and the model predicted that a reverse-circulation cementing (RCC) operation would be successful.RCC is a method of pumping cement down the annulus and receiving returns inside the casing. One advantage of reverse circulating is that the ECD is reduced and less pressure is exerted on the formation. This will help reduce or eliminate cement losses into weak formations.Placing the cement down the annulus appeared to be feasible with the computer model but to conduct the operation in the field, other challenges were addressed. In a reverse operation, the float valve is removed or sheared out before pumping cement. This is not of concern with a normal casing * Formerly employed by Devon-Canada

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“…General RCC can provide the following advantages in wells meeting the requirements for the method: 1,2 • Shorter slurry thickening times.…”

Section: Reverse-circulation Cementingmentioning

confidence: 99%

Reverse-Circulation Cementing To Seal a Tight Liner Lap

et al. 2007

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“…Reverse circulation of cement placement technique (RCCPT) has been offered as an alternative to eliminate some of the problems experienced when cementing potential lost circulation zones (1)(2)(3)(4)(5) .…”

Section: Introductionmentioning

confidence: 99%

“…In a recent paper, Davies et al (5) also discussed the benefits and shortcomings of RCCPT in relation to fluid friction, cement slurry design, location safety, and zonal isolation. They presented a case history to show how RCCPT's strengths are obtained, while shortcomings are minimized.…”

Section: Introductionmentioning

confidence: 99%

Reverse Circulation Placement Technique vs. Conventional Placement Technique: A Comparative Study of Cement Job Hydraulics Design

Kuru

Seatter

2005

Journal of Canadian Petroleum Technology

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Reverse circulation cement placement technique (RCCPT) has been suggested asan alternative for providing proper annular coverage for lost circulationzones. It is generally believed that RCCPT helps minimize the circulationpressure and hence, allows cement placement with no apparent losses. A basic hydraulic design study is conducted to determine the anticipatedpressure losses during the cement jobs run by using both the RCCPT and theconventional cement circulation placement technique (CCCPT). Results have shown that, for each design case (i.e., wellbore geometry andthe rheology of cement slurry), there is a critical depth above which theequivalent circulating pressure (ECD) with RCCPT can be higher than ECD with CCCPT. Examples of typical cement job design calculations are provided toillustrate the changing ECDs as a function of depth during both RCCPT and CCCPT. Introduction Lost circulation is one of the most common problems encountered whencementing a well. The problem becomes increasingly critical, particularly whencementing fractured formations such as the ones encountered in geothermalwells, and coal bed methane wells, or low fracture gradient zones near sea bedsin offshore wells. Primary cementing of these zones using the conventionalcement circulation placement technique (CCCPT) has been very difficult, evenwith lightweight and foamed cement. Reverse circulation of cement placement technique (RCCPT) has been offeredas an alternative to eliminate some of the problems experienced when cementingpotential lost circulation zones(1–5). Marquarie and Brisac(1) reported successful applications of RCCPT in the North-Hassi-Messaoud Field in Algeria. Using RCCPT, they were able to cement aweak Triassic formation above the casing shoe without allowing the plasticclays (above the weak zone) to extrude and salt water to enter the well. Griffith et al.(2) conducted large scale experimental tests to investigatethe advantages of RCCPT. They have suggested that RCCPT is a viable option tolower equivalent circulating densities during the cementing process. They havealso found that reverse circulation of cement on primary cementation neitherincreases nor decreases the displacement efficiency. Griffith et al.(2) alsooutlined a procedure for a typical reverse circulation cementing operationconducted by coal bed methane producers in the area of Trinidad, CO, in the U.S.

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A Numerical Study of Density-Unstable Reverse Circulation Displacement for Primary Cementing

Skadsem

Kragset

2022

Journal of Energy Resources Technology

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Primary cementing of the casing string is the operation where the annular space behind the casing is displaced to a cement slurry. Once hardened, the cement should form a solid annular barrier and provide zonal isolation behind the casing. Reverse circulation cementing involves injecting the cement slurry directly into the annulus that is to be cemented, displacing drilling fluid down the well. This will normally represent a density-unstable situation with an increased risk of inter-mixing of fluids and slurry contamination compared to conventional circulation cementing. This study addresses the reverse circulation displacement mechanics, and is based on a reverse circulation field case where the quality of the hardened cement has previously been established by characterization of two retrieved joints. We use 3D numerical simulations to study possible displacement conditions and compare findings qualitatively to the actual cement. Additional simulations indicate the importance of imposed flow rate and viscous stresses in suppressing the destabilizing effect of buoyancy. A simplified one-dimensional displacement model provides reasonable predictions of the front propagation speed in vertical, concentric annuli and correct identification of conditions that result in backflow of lighter fluid. To the best of our knowledge, this study is the first effort to better understand density-unstable displacements in annular geometries.

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Reverse Circulation of Primary Cementing Jobs—Evaluation and Case History

Cited by 9 publications

References 6 publications

Reverse-Circulation Cementing To Seal a Tight Liner Lap

Reverse-Circulation Cementing To Seal a Tight Liner Lap

Reverse Circulation Placement Technique vs. Conventional Placement Technique: A Comparative Study of Cement Job Hydraulics Design

A Numerical Study of Density-Unstable Reverse Circulation Displacement for Primary Cementing

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